This flu season, women’s healthcare providers play a particularly vital role in advising pregnant women to receive the influenza vaccination.

Changes in the immune system, heart, and lungs during pregnancy make pregnant women (and those up to 2 weeks postpartum) more prone to severe illness from influenza. The flu during pregnancy increases the chance of hospitalization and adverse neonatal outcomes, such as low birthweight and preterm birth. Since 2010, the CDC estimates that flu has resulted in 140,000 to 710,000 hospitalizations annually. During the 2009 H1N1 influenza pandemic in the United States, pregnant women were more than four times more likely to be hospitalized than the general population and had higher mortality rates.

Vaccination during pregnancy is the best way to prevent serious illness caused by influenza. Flu vaccination during pregnancy also provides important protections to the fetus. Because the flu vaccine is not approved for use in infants younger than 6 months, maternal vaccination is the most effective strategy to protect infants. Through maternal vaccination, influenza antibodies are passed from the mother through the placenta to the fetus.